Fiber-optic connector for releasably coupling an optical fiber to an optoelectronic device and related method

ABSTRACT

A module for coupling to a fiber-optic cable includes an optoelectronic assembly that includes a bracket and a metal receptacle. The metal receptacle includes an attachment member operable to releasably connect the receptacle to the bracket, an alignment end operable to receive an alignment device, and a connector end operable to releasably connect to the fiber-optic cable and to orient the cable with the alignment device. The metal receptacle can suppress EMI and can typically withstand higher temperatures than most plastic materials. Thus, when subject to high temperatures, the receptacle typically will not expel gas that can fog a lens or deform. The attachment member allows one to releasably connect the receptacle to an optoelectronic assembly without fixing the receptacle to the assembly with adhesive. Thus, the receptacle can be mounted to an optoelectronic assembly quickly and without an alignment fixture.

FIELD OF THE INVENTION

[0001] The invention generally relates to fiber-optic communicationsystems, and more particularly to a fiber-optic connector thatreleasably couples optical fibers to an optoelectronic device in afiber-optic communication system.

BACKGROUND

[0002] Fiber-optic communication systems are commonly used fortransmitting/receiving data. Because as of yet there are no practicaloptical computers, the data typically originates as an electrical signalthat a transmitter converts into an optical (light) signal fortransmission over an optical fiber. A receiver then converts the opticalsignal back into an electronic signal for processing of the data. Morespecifically, an optoelectronic light source such as a light emitterdiode (LED) converts the electrical signal in the optical signal, and anoptoelectronic light detector such as a photo diode converts the opticalsignal back into an electrical signal.

[0003]FIG. 1 is an exploded view of a conventional optoelectronic module10 for transmitting optical signals to and receiving optical signalsfrom a fiber-optic cable 12 that includes one or more optical fibers 14(only one shown). The module 10 includes an optoelectronictransmit/receive assembly 16 and a fiber-optic interface 18 forreleasably coupling the fiber-optic cable 12 to the assembly 16. Theinterface 18 includes a receptacle 20 that is typically made of plasticand that is mounted to the optoelectronic assembly 16. The receptacle 20includes latches 22 that mate with a connector 24 for releasablyconnecting the cable 12 to the receptacle 20. The interface 18 alsoincludes an alignment device 25 and lens 26 for respectively aligning aphoto diode/LED 30 with the fiber 14 and for focusing the optical beamformed by the signal.

[0004] To assemble the module 10, first the lens 26 is mounted to thealignment device 25, and then the alignment device 25 is mounted to theoptoelectronic assembly 16 by inserting the guide pins 28 (only oneshown) into corresponding holes (not shown) in the panel 32 of theassembly 16. Next, the lens 26 is optically aligned with the component30. Once the lens and component 30 are aligned, the alignment device 25is fixed to the panel 32 with adhesive. Next, the receptacle 20 ismounted over and aligned with the alignment device 25 and fixed in placewith adhesive. Because the optical alignment of the fiber 14 with thecomponent 30 must be relatively precise—within microns—a fixture (notshown) is used to keep the alignment device 25 and the receptacle 20 inalignment while the adhesive cures.

[0005] Although, the module 10 is useful in many applications it may beunsuitable for certain situations as described below.

[0006] Unfortunately, because the receptacle 20 is typically made fromplastic, mounting the module 10 to a system printed-circuit board (notshown) or using the module 10 for an extended period of time may damagethe fiber-optic interface 18. To mount the module 10 to a board, themodule 10 is typically soldered to the board. Soldering generates heatthat can raise the temperature of the interface 18 in excess of 230° C.If the temperature of the receptacle 20 is high enough, the plastic canrelease gas or deform the connector latches 22 that releasably retainthe cable 12 to the interface 18. Gas released by the plastic can fogthe lens 26, which may distort or prevent an optical signal from passingbetween the fiber 14 and the component 30. Deformed connector latches 22may cause the fiber 14 to misalign with the lens 26 when attached to thereceptacle 20, or may altogether prevent connection of the cable 12 tothe interface 18.

[0007] In addition, it is sometimes desired that the receptacle 20suppress electromagnetic interference (EMI) generated by the circuitry(not shown) of the assembly 16. But because plastic typically cannotsuppress EMI, the receptacle 20 must be appropriately modified. Typicalmodifications include either plating the receptacle 20 with a metal ormixing metal into the plastic material used to make the receptacle 20.These modifications, however, are typically expensive, and thustypically increase the cost of the interface 18.

[0008] Moreover, the process of mounting the receptacle 20 to theassembly 16 is not simple. Because this process entails gluing thereceptacle 20 and alignment device 25 to the panel 32 using an alignmentfixture (not shown), the time required to assemble the module 10includes the time the adhesive takes to cure and the time one takes toassemble the module 10 in the fixture and remove the module 10 from thefixture. Thus, the time spent assembling and removing the module 10 fromthe fixture may also increase the cost of the module 10.

[0009] The module is further discussed in U.S. patent application Ser.No. 10/174,002 titled ACTIVELY ALIGNED OPTOELECTRONIC DEVICE and filed17 Jun. 2002, which is incorporated by reference.

[0010] In view of the foregoing, there is a need for a fiber-opticreceptacle that can withstand high temperatures, withstand use over anextended period of time, suppress EMI, and be easily mounted.

SUMMARY

[0011] In one aspect of the invention, a module for coupling to afiber-optic cable includes an optoelectronic assembly that includes abracket and a metal receptacle. The metal receptacle includes anattachment member operable to releasably connect the receptacle to thebracket, an alignment end operable to receive an alignment device, and aconnector end operable to releasably connect to the fiber-optic cableand to orient the cable with the alignment device.

[0012] A metal receptacle can suppress EMI and can typically withstandhigher temperatures than most plastic materials. Thus, when subject tohigh temperatures, the receptacle typically will not expel gas that canfog a lens or deform.

[0013] Furthermore, the attachment member allows one to releaseablyconnect the receptacle to an optoelectronic assembly without fixing thereceptacle to the assembly with adhesive. Thus, the receptacle canretain other parts of the optoelectronic assembly while the adhesivefixing the other parts cure. Furthermore, the receptacle can be mountedto an optoelectronic assembly quickly and without an alignment fixture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The features of the present invention which are believed to benovel are set forth with particularity in the appended claims. Theinvention, together with further objects and advantages thereof, maybest be understood by making reference to the following descriptiontaken in conjunction with the accompanying drawings, in the severalfigures of which like referenced numerals identify like elements, andwherein:

[0015]FIG. 1 is an exploded view of a conventional optoelectronicmodule.

[0016]FIG. 2 is an exploded view of an optoelectronic moduleincorporating a receptacle according to an embodiment of the invention.

[0017]FIG. 3 is a perspective view of the alignment end of thereceptacle of FIG. 2, according to an embodiment of the invention.

[0018]FIG. 4 is a perspective view of the connector end of thereceptacle of FIG. 2, according to an embodiment of the invention.

[0019]FIG. 5 is a cross-sectional view of the receptacle of FIG. 2.

DETAILED DESCRIPTION

[0020] In the following detailed description of exemplary embodiments ofthe invention, reference is made to the accompanying drawings, whichform a part hereof. The detailed description and the drawings illustratespecific exemplary embodiments by which the invention may be practiced.These embodiments are described in sufficient detail to enable thoseskilled in the art to practice the invention. It is understood thatother embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the present invention. Thefollowing detailed description is therefore not to be taken in alimiting sense, and the scope of the present invention is defined onlyby the appended claims.

[0021]FIG. 2 is an exploded view of an optoelectronic module 40incorporating a fiber-optic interface 42 according to an embodiment ofthe invention. The interface 42 releasably couples a fiber-optic cable44, which incorporates one or more optical fibers 46 (only one shown),to the module 40 in an optically aligned position with a photo-diode/LEDcomponent 48 of an optoelectronic assembly 50. Thus, the assembly 50 cantransmit and receive optical signals to and from the optical fibers 46,and consequently, other optoelectronic devices (not shown) and systems(not shown) also coupled to the cable 44.

[0022] The fiber-optic interface 42 includes a receptacle 52 (discussedin greater detail in conjunction with FIGS. 3-5) that is releasablyconnectable to a bracket 51, which is part of the assembly 50. Thereceptacle 52 is made from metal that can withstand hightemperatures—typically around 230° C. and higher—and suppress EMI. Inone embodiment, the receptacle 52 is made from stainless steel thatincludes chromium and nickel and that is commonly identified as 17-4 PH.The receptacle 52 can be fabricated using any conventional process, suchas metal injection molding. Because the receptacle 52 is made of metalmaterial, high temperatures like those frequently found when the module40 is soldered to a circuit board (not shown), or when the module 40 isused for an extended period of time in high temperature environments,will not cause the receptacle 52 to expel gas that can fog the lensarray 66 or the end of the fiber 46. Furthermore, the receptacle 52 willnot deform, and thus can retain fiber 46 in an optically alignedposition with the component 48.

[0023] Still referring to FIG. 2, in one embodiment, the receptacle 52includes an alignment end 54, a connector end 56, and two attachmentmembers 58 (only one shown) for releasably connecting the receptacle 52to the bracket 51. With the attachment member 58, the receptacle 52 canbe releasably coupled to the optoelectronic assembly 50 withoutadhesive. Thus, the receptacle 52 can be used as a fixture to hold otherparts of the optoelectronic module 40, such as the panel 61, in positionwhile the adhesive fixing the other parts cure. Furthermore, a separatealignment fixture is not needed and the time required to mount theinterface 42 to the assembly 50 is often reduced.

[0024] The alignment end 54 receives the alignment device 60 andcoarsely aligns the connector end 56 with the alignment device 60. Theconnector end 56 releasably connects the cable connector 62, which inone embodiment is a conventional optic fiber Mechanical Transfer Plugarray connector (MTP), to the receptacle 52 with connector-end latches64 that mate with the MTP connector 62. The connector end 56 alsoorients the cable 44 with the alignment device 60, which opticallyaligns the optical fibers 46 with the component 48 as discussed below.Thus, when the cable 44 is releasably connected to the module 40, theoptical fibers 46 are optically aligned with the component 48.

[0025] Still referring to FIG. 2, in one embodiment the interface 42includes the alignment device 60 and a lens array 66 mounted on thealignment device 60 for focusing the optical signals traveling to andfrom the fibers 46. The lens array 66 includes a number of opticalelements that corresponds to the number of optical fibers 46 exposed atthe end of the cable 44. Two device alignment pins 68 (only one shown)extend from a mating portion 72 and are inserted into correspondingholes (not shown) in the assembly 50 to locate the lens array 66 inclose proximity to the component 48. As discussed in the U.S. patentapplication Ser. No. 10/174,002 (already incorporated above), thealignment device 60 is moved in the X, Y and ⊖ directions as necessaryto optically align the elements of the lens array 66 with thecorresponding elements of the component 48. The alignment device 60 isthen fixed to the assembly 50 with adhesive.

[0026] To optically align the optical fibers 46 with the lens array 66,the alignment device 60 includes two connector alignment pins 70 (onlyone shown) extending from the mating portion 72. When the cable 44 isreleasably attached to the receptacle 52, the connector alignment pins70 are inserted into corresponding holes (not shown) in the MTPconnector 62. The pins 70 are sized to allow very little movement of theMTP connector 62 in the X, Y, and ⊖ directions and each pin 70 includesa chamfer (not shown) on the end of the pin opposite the mating portion72. The chamfer allows some initial tolerance in the alignment of thepins 70 with the corresponding holes of the MTP connector 62, and thus,allows the connector end 56 of the receptacle 52 to orient the fibers 46with the alignment device 60. For example, in one embodiment, the basediameter of each pin 70 is 300 microns, and the chamfer runs from thelongitudinal center of the pin 70 to the tip of the pin 70.Consequently, in one embodiment the MTP connector 62 can be initiallymisaligned with the alignment device 60 up to 149 microns in the X or Ydirections and still become optically aligned with the alignment device60 when the MTP connector 62 is fully inserted in the connector end 56.That is, the center of each pin 70 can be initially misaligned from thecenter of the corresponding hole in the MTP connector 62 by up to 149microns, and the chamfered tips will still enter the holes. As the pins10 are further inserted into the holes, the pins' 70 increasing diameterforces the MTP connector 62 into alignment with the device 60.

[0027] Still referring to FIG. 2, in one embodiment, the bracket 51 isalso made of a metal material that can withstand high temperatures andsuppress EMI. The bracket 51 includes a mating surface 74 that is fixedto the panel 61 of the assembly 50 with conventional adhesive, and fourlegs 76 (only two shown) that are fixed to the bottom panel of theassembly 50 with conventional adhesive. The bracket 51 also includesfour bracket indentations 78 (only two shown) each matable with one ofthe respective bosses (not shown but discussed in greater detail inconjunction with FIG. 3) of the attachment member 58 to releasablyconnect the receptacle 52 to the bracket 51. The bosses are forced intorespective bracket indentations by elastic deformation of the attachmentmember 58 when the receptacle 52 is inserted onto the bracket 51.

[0028] Still referring to FIG. 2, in one embodiment, the interface 42includes a conductive ground clip 79 insertable over the connector end56 of the receptacle 52 for grounding the receptacle 52. Mostoptoelectronic systems ground components and circuits to the case orchasis of the system. But because most receptacles are made of plastic,most cases or chasis are not designed to contact the receptacle 52 whenthe module 40 is mounted to the system. Consequently, a device like thegrounding clip 79 may be included to electrically couple the receptacleto the case, chasis, or other ground point of an optoelectronic system.

[0029] Still referring to FIG. 2, in one embodiment, the fiber-opticinterface 42 is mounted to the optoelectronic assembly 50 as follows.First, the four legs 76 of the bracket 51 are fixed to theoptoelectronic assembly 50 as previously discussed. Next, the alignmentdevice 60 is mounted to the panel 61 and the lens array 66 is opticallyaligned with the component 48 as previously discussed. Once the lensarray 66 is optically aligned, adhesive is injected between thealignment device 60 and the panel 61 and cured to fix the alignmentdevice 60 to the panel 61. Next, adhesive is inserted between the panel61 and the mating surface 74 of the bracket 51. The receptacle 52 isthen connected to the bracket 51 and holds the panel 61 in place. Atemporary spring (not shown) is placed between the receptacle 52 and thepanel 61 to press the panel 61 toward the mating surface 74 while theadhesive cures. After the adhesive cures, the temporary spring isremoved. Because of the attachment member 58 and the bracketindentations 78, the receptacle 52 does not have to be fixed to theassembly 50 with adhesive and then held in place with a fixture whilethe adhesive cures. Alternatively, the receptacle 52 can be glued to thepanel 61. But again, because of the member 58 and indentations 78 nofixture is required to hold the receptacle 52 while the adhesive cures.

[0030]FIG. 3 is a perspective view of the alignment end 54 of thereceptacle 52 of FIG. 2, according to an embodiment of the invention.The alignment end 54 receives the alignment device 60 (FIG. 2) andcoarsely aligns the connector end 56 with the alignment device 60 in theX, Y and ⊖ directions as discussed above in conjunction with FIG.2.

[0031] The configuration of the alignment end 54 depends on the shape ofthe alignment device 60 (FIG.2). In one embodiment, the alignment end 54includes an alignment-end interior wall 80 and surface 82 that define analignment-end cavity 84 sized to receive the mating portion 72 of thealignment device 60. When the receptacle 52 is mounted to theoptoelectronic assembly 50 with the alignment device 60 disposed betweenthem, the cavity 84 permits very little movement of the mating portion72 in the X, Y and ⊖ directions. In addition, the mating portion 72 mayor may not contact the surface 82.

[0032] Still referring to FIG. 3, in one embodiment, the receptacle 52includes two attachment members 58 each including two bosses 86 (onlythree shown) for mating with the respective bracket indentations 78(FIG. 2) to releasably connect the receptacle 52 to the bracket 51 (FIG.2). The attachment members 58 extend from the alignment end 54 away fromthe connector end 56. When the receptacle 52 is releasably mounted tothe bracket 51, the attachment members 58 are forced apart. Theresulting elastic deformation in the material of each attachment member58 forces each boss 86 into their respective indentations 78 in thebracket 51.

[0033]FIGS. 4 and 5 are views of the receptacle 52 showing the connectorend 56 according to an embodiment of the invention. FIG. 4 is aperspective view of the receptacle 52, and FIG. 5 is a cross-sectionalview of the receptacle 52. The connector end 56 releasably connects thefiber-optic cable 44 (FIG. 2) to the receptacle 52, and orients thecable for optical alignment of the fibers 46 (FIG.2) with the lens array66 (FIG.2) via the alignment device 60 (FIG. 2).

[0034] Referring to FIGS. 4 and 5, the configuration of the connectorend 56 depends on the type of connector used by the cable 44. In oneembodiment, the connector end 56 includes a connector-end interior wall88 that defines a connector-end cavity 90 sized to receive the end ofthe MTP connector 62 (FIG. 2), and two connector-end latches 64 thatmate with indentations (not shown) included in the MTP connector. Toorient the cable 44 for optical alignment, the connector-end-cavity 90is sized to permit little movement of the MTP connector 62 in the X, Y,and ⊖ directions. Furthermore, the connector-end cavity 90 includes agroove 92 sized to mate with a key (84 in FIG. 2) on the MTP connector62 when the MTP connector is inserted into the connector-end cavity 90.Thus, the connector end 56 of the receptacle 52 will receive the MTPconnector only if the MTP connector 62 is properly oriented with thealignment device 60.

[0035] Still referring to FIGS. 4 and 5, in one embodiment, theconnector-end latches 64 are disposed in the connector-end cavity 90 andeach includes a tooth 94 that mates with a respective indentationincluded in the MTP connector 62. When the MTP connector 62 is insertedinto the connector-end cavity 90, the connector-end latches 64 areforced toward the connector-end interior wall 88. The resulting elasticdeformation in the material of the connector-end latches 64 forces eachtooth 94 into their respective indentations in the MTP connector 62.Thus, the MTP connector 62 can be releasably connected to the receptacle52.

[0036] Referring to FIG. 5, in one embodiment, the connector-end latches64 extend from a shoulder 96 in the connector end 56 substantiallyparallel to the connector-end interior wall 88, and the tooth 94 on eachlatch faces the tooth 94 of the other connector latch 64. When the MTPconnector is inserted into the connector-end cavity 90, the MTPconnector 62 contacts the mating portion 72 of the alignment device 60(FIG. 2) to align the optical fibers 46 (FIG. 2) with the lens array 66(FIG. 2) in the Z direction. That is, the alignment device 60 spaces thefibers 46 a proper distance from the lens array 66.

What is claimed is:
 1. A metal receptacle for coupling a fiber-opticcable to an optoelectronic assembly, comprising: an attachment memberoperable to releasably connect the receptacle to the optoelectronicassembly, an alignment end operable to receive an alignment device; anda connector end operable to releasably connect to the fiber-optic cableand to orient the cable with the alignment device.
 2. The metalreceptacle of claim 1 wherein the receptacle comprises stainless steel.3. The metal receptacle of claim 2 wherein the stainless steel comprises17-4PH stainless steel.
 4. The module of claim 1 wherein the receptacleis operable to suppress EMI.
 5. An interface for coupling a fiber-opticcable to an optoelectronic assembly and for optically aligning the cablewith a component of the optoelectronic assembly, comprising: analignment device operable to optically align the fiber-optic cable tothe component of the optoelectronic assembly; and a metal receptacleincluding, an attachment member operable to releasably connect thereceptacle to the optoelectronic assembly, an alignment end operable toreceive the alignment device; and a connector end operable to releasablyconnect to the fiber-optic cable and to orient the cable with thealignment device;
 6. The interface of claim 5 wherein the alignmentdevice includes: a connector alignment pin operable to optically alignthe fiber-optic cable to the alignment device by inserting the connectoralignment pin into a connector of the fiber cable; and a devicealignment pin operable to optically align the alignment device to thecomponent by inserting the device alignment pin into the optoelectronicdevice.
 7. The interface of claim 5 wherein the alignment deviceincludes: a connector alignment pin operable to optically align thefiber-optic cable to the alignment device by inserting the connectoralignment pin into a connector of the fiber cable; a device alignmentpin operable to optically align the alignment device to the component byinserting the device alignment pin into the optoelectronic device; and alens array for focusing the optical signals traveling to and from thefiber-optic cable.
 8. A fiber-optic module for coupling to a fiber-opticcable, the module comprising: an optoelectronic assembly that includes abracket; and; a metal receptacle including, an attachment memberoperable to releasably connect the receptacle to the bracket, analignment end operable to receive an alignment device; and a connectorend operable to releasably connect to the fiber-optic cable and toorient the cable with the alignment device.
 9. The module of claim 8wherein the receptacle is operable to mount the alignment device to theoptoelectronic assembly.
 10. The module of claim 8 wherein thereceptacle includes two attachment members operable to releasablyconnect the receptacle to the bracket.
 11. The module of claim 8wherein: the bracket includes an indentation; and the attachment memberextends from the alignment end away from the connector end and includesa boss insertable into the indentation for attaching the receptacle tothe bracket.
 12. The module of claim 8 wherein: the bracket includesfour indentations; and the receptacle includes two attachment memberseach extending from the alignment end away from the connector end andeach including two bosses, wherein each boss is insertable into arespective one of the four indentations for attaching the receptacle tothe bracket.
 13. The module of claim 8 wherein: the receptacle includestwo attachment members, each extending from the alignment end and awayfrom the connector end; and the alignment end includes an alignment-endinterior wall that defines an alignment-end cavity disposed between theattachment members.
 14. The module of claim 8 wherein the alignment endcoarsely aligns the connector end with the alignment device when thealignment device is inserted into the alignment end.
 15. The module ofclaim 8 wherein the alignment end includes an alignment-end interiorwall and a surface that define an alignment-end cavity, wherein when thealignment device is inserted into the alignment-end cavity, thereceptacle is aligned with the alignment device along an X, Y and ⊖ axesof alignment.
 16. The module of claim 8 wherein the connector endincludes a connector-end latch matable with a connector of thefiber-optic cable for releasably connecting the cable to the receptacle.17. The module of claim 8 wherein the connector-end includes aconnector-end interior wall that defines a connector-end cavity, whereinwhen the fiber-optic cable is inserted into the connector-end cavity,the connector-end cavity orients the cable for optical alignment withthe alignment device.
 18. The module of claim 8 wherein the connectorend includes: a connector-end interior wall that defines a connector-endcavity, wherein when the fiber-optic cable is inserted into theconnector-end cavity, the connector-end cavity orients the cable foroptical alignment with an alignment device; a shoulder protruding fromthe connector-end interior wall; and two connector-end latches eachextending from the shoulder parallel or substantially parallel to theconnector-end interior wall and each including a tooth insertable intoan indentation of a connector of the cable for releasably retaining thecable to the module.
 19. The metal receptacle of claim 8 furthercomprising a clip contacting the receptacle for grounding thereceptacle.
 20. A method for mounting a fiber-optic interface to anoptoelectronic assembly, the method comprising: mounting a leg of abracket to the optoelectronic assembly; placing an alignment device onthe optoelectronic assembly; optically aligning the alignment device toa component of the optoelectronic assembly; fixing the optically alignedalignment device to the optoelectronic assembly; mounting a matingportion of the bracket to the optoelectronic assembly; and connecting areceptacle to the bracket by inserting a boss of an attachment member ofthe receptacle into an indentation of the bracket to hold the receptacleto the bracket.
 21. The method of claim 20 wherein fixing the alignmentdevice to the optoelectronic assembly includes: applying an adhesivebetween the alignment device and the optoelectronic assembly; and curingthe adhesive.
 22. The method of claim 20 wherein mounting the matingportion of the bracket to the optoelectronic assembly includes: applyingan adhesive between the mating portion and the optoelectronic assembly;holding the optoelectronic assembly in optical alignment with thereceptacle by connecting the receptacle to the bracket; and curing theadhesive.